Image Builder Design Tao Qian UIUC April 10, 2007.
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Transcript of Image Builder Design Tao Qian UIUC April 10, 2007.
Image Builder Design
Tao QianUIUC
April 10, 2007
Tao Qian2
Basic Structure
The Image Builder will consist of five nodes and a supervisor:
IB supervisor layer -- 1 Linux system
Maintain the current status information of IB nodes
Coordinate the connections between monsoon PANs and IB node
IB – five nodes
Collect pixel data from science/focus PANs
Combine pixel data with metadata
Form multi-extension FITS file and deliver to downstream
Tao Qian3
Basic Idea
1. IB consists of a set of Linux boxes
2. One IB node assembles data from five science/focus PANs at any time
3. Current active IB node is determined by IB supervisor
4. Connection between PANs and IB are through TCP/IP sockets
5. IB is server; PANs are clients
6. Clients push the pixel data and metadata into IB
7. IB stuffs the data into the shared memory
Tao Qian4
Architecture
Ethernet Switch
Data Flow
• Image Builder Supervisor directs pixel data to one IB machine at any time
PAN PAN
IB IB IB IB IB IB supervisor
message
Tao Qian5
Primary Processes in IB
1. collector: • Listen to connection from clients (PANs) • Stuff the pixel data into the shared memory cache• Listen for commands from supervisor layer, reporting the current
status
2. sharedMemoryManager:• Organize the shared memory cache• Reorient the memory page to account for CCD readout direction• Provide access pointer for other processes
3. pixelFeed• Gather global metadata from database• Assemble image from the shared memory into FITS format• Send file to DTS through sockets
Tao Qian6
Data Flow Testing (1)
• A toy model has been developed • Client on (storm.des.hep.uiuc.edu) Pentium 4 Linux machine• Server on (cyclone.des.hep.uiuc.edu) Pentium 4 Linux machine
Transferring data from half full PAN 18/2:
numCcd = 9;
nx = 2248; rows pixel
ny = 4146; columns pixel
4 bytes/pixel
Total data = 2248 * 4146 *4 *9
= 335, 527, 488 bytes
The data is equivalent to 9 CCD pixel data with 4 bytes per pixel.
Tao Qian7
Data Flow Testing (2)
Packet size (bytes)
Action Trial 1 (sec)
Trial 2 (sec)
Trial 3 (sec)
Average (sec)
Average Rate
(1/sec)
1024
Recv 29 28 29 29 11.57 Mbytes
92.56 Mbits
&Save 81 81 81
4096
Recv 28.52 28.15 27.84 28.17 11.91 MBytes
95.28 Mbits
&Save 100 100 100
8192
Recv 30.40 29.41 28.91 29.57 11.34 MBytes
90.7 Mbits
&Save 100.13 104.88 102.89 102.63
Ethernet switch 10Mb/100Mbps, Ethernet Adaptors (1Gbps)Received data : 335, 527, 488 bytes
Estimation: Total time = (~30*2)/PAN x 5 PANs = 300 seconds with current switch.Need a faster Ethernet switch to repeat the test!!!
Tao Qian8
Data Flow Testing (3)
• Two clients (tempest and storm sending data)• One server (cyclone receiving data through two different ports)• Tempest started the transferring 1 seconds earlier and finished
in 31 seconds, with rate ~90Mbps• Storm started the process late and the connection was set, but
the transmission was almost halted, and continued after tempest was done
• Total time was doubled w.r.t. one client one server case.
Tempest Storm
Time for 9 CCD data 31 seconds 61 seconds
Tao Qian9
Estimation of DHS node
• Assumptions– 1 gigabit/second switch, actual 30% efficiency (conservative)
• R = 300 bits/sec
– Pixel size per CCD (p = 2248*4146 = 9,320,208 pixels)– 4 bytes per pixel (n = 4)– 18 full size CCDs per PAN (C = 18)– Total Bytes to transfer per PAN (B=p*n*C= 671,054,976 bytes)– Total 5 PANs (N=5)– Transfer time t1=B*N/R=90 seconds (<100 sec Exposure) (OK!)– Time for data operation (e.g. focus) in DHS t2 = 200 (s)– Time for data output to DTS t3= 90 (s)
Node = (90 + 200 + 90)/100 = 4
Tao Qian10
Next Step
• Write Interface Control document• Test the client code and implant it into MONSOON
– Link the correct dhsUtil.lib in MONSOON which will send data to DHS (modify the monsoon library)
• Develop the server– Develop based on DHS software from NEWFIRM
• Design IB supervisor layer
Tao Qian11
Reference
• DES image builder design follows data handling system and data capture agency software in NEWFIRM project at NOAO
• In NEWFIRM, one Data Handling System matches one PAN
• The data are delivered to one Data Capture Agent machine to form multi extension FITS file